The present invention relates to outdoor lighting controls for automatically turning a light on and off at night and is more particularly directed to a control technique for adjusting the length of time a light stays on at night to take into account the variation in the length of the night with the seasons.
A popular form of outdoor lighting fixture turns itself on automatically at night. The lighting fixture includes a light sensor for detecting the presence of daylight. Some such lighting fixtures are able to operate in several different modes. In one mode, commonly called dusk-to-dawn mode, the fixture comes on automatically when the daylight sensor no longer senses the presence of daylight and turns off automatically when the sensor first begins to detect daylight at dawn. In another mode, commonly called accent mode, the lighting fixture comes on automatically at night at a reduced level of illumination so as to provide a low level of accent lighting. Such a mode is commonly used in conjunction with a motion detector. The lighting fixture comes on at nightfall at the reduced level of illumination, and then when motion is detected, the fixture comes on at the full-brightness level, returning to the reduced level of illumination shortly after motion is no longer detected.
Some models of outdoor lighting fixtures also include a switch, which allows the user to manually select the length of time the light stays on after it first turns on automatically. For example, the user may be presented with a choice of 3, 5 or 7 hours on-time or all night operation.
Other forms of switches are known which may be wired into the electrical circuit providing power to the outdoor lighting fixture. Such switches allow the user to manually set the times at which the lighting fixture turns on and off.
There is a problem with such control mechanisms, however, in those latitudes away from the equator where the length of the day (and night) varies with the season. In the summer months when the day is longer, the user may only want the lighting fixture to stay on for two or three hours. During the winter months when it may already be dark before dinnertime, the user may want the light to stay on for six or more hours. With the popular outdoor lighting fixtures presently available with automatic turn-on control, the user has to manually reset the on-time duration as the length of the day changes with the seasons.